An aircraft generally comprises a number of electrical machines distributed throughout the aircraft to fulfill a set of miscellaneous functions. Electrical machines are, for example, known that are dedicated to the starting up of a propulsion turbine, to an air conditioning set for the passenger compartment of the aircraft, or even dedicated to the operation of the aerodynamic control surfaces of the aircraft. For these functions, there are notably direct current electrical machines, asynchronous or synchronous, three-phase, six-phase or, more generally, polyphase. These electrical machines consume electrical power available on the onboard network of the aircraft, and, for example, supplied by a generator linked to a turbine or else supplied by an airport network when the aircraft is on the ground.
It is known that it is essential to have reliable information on the position of the rotor of the electrical machine. Any measurement error on the position significantly increases the electrical losses. Typically, an error of less than 5% on the real position is generally sought, the impacts on the machine being considered to be acceptable (weight penalty linked to the machine overdimensioning, additional costs, notably for cooling, etc.). The electrical machines implemented on board an aircraft exhibit high rotation speeds, of the order of 10 000 to 50 000 rpm, making it necessary to have rotor position information at high frequency, typically of the order of 8 to 40 kHz. There are a number of techniques for evaluating the position of the rotor. A variety of sensors are known providing a physical measurement of the position, there are also computation means making it possible to evaluate this position as a function of the voltages and currents measured in each of the phases of the machine.
In a conventional electrical architecture of an aircraft, each electrical machine has an inverter linked to the onboard network which formats the signal supplying each of the phases in accordance with the needs of the machine. In the case of an electrical machine equipped with a position sensor, the inverter relies on the rotor position information supplied by the position sensor to determine the stator current and voltage setpoints, and possibly the rotor current and voltage setpoints for wound rotor machines.
This architecture in which an inverter is assigned to a single electrical machine has limitations that the invention seeks to resolve. For example, the inverter dedicated to an electrical machine responsible for starting the turbine is used only when the aircraft is on the ground prior to take-off. In flight, the unused inverter represents an unnecessary weight and cost overhead. Similarly, a failure of an inverter renders an otherwise operational electrical machine unusable. For these reasons, it is desirable to have a more modular electrical architecture, which would make it possible to modify the assignment of an inverter between a number of machines. A modular power rack is envisaged controlling the supply of a set of electrical machines distributed throughout the aircraft by means of a set of inverters. Producing such a modular rack comes up against the difficulties of management of the position information for the set of machines, and in particular the pooling of the high frequency position information items and their transmission without degradation (error, delay) to the inverters concerned.